In ophthalmic surgery a series of methods are known which make possible, with or without additional invasive procedures, an abrasion of parts of the cornea surface to correct sight defects. In particular the PRK, LASIK and LASEK methods may be named here.
Traditionally, fine tuning of the refractive correction is carried out in the case of sphere and cylinder on the basis of subjective phoropter measurements, because the best possible standard correction can thereby take place in individually secured manner without taking higher aberrations into account. In the meantime, higher aberrations can be subjectively evaluated with the help of a so-called phase-plate phoropter which is known for example from DE10103763, or adaptive phoropters, and used for refractive correction.
A problem when carrying out such treatment procedures is the fact that slight changes in the treatment parameters can have a marked effect on the success of the treatment. Reliance is usually placed here on the experience of the doctor in attendance, the assumption being that he is aware of the significance of the effect of all the parameters.